This using programmable micro controllers to add "behaviors" to pieces keeps getting interestinger and interestinger.
This one started while playing with a small servo. Hit on having the servo's arm move randomly somewhere within about a
70 arc. Watching it dart back and forth reminded me of a "behavior" - the eyes of a speed freak - darting around, unable to stay focused on anything for more than a second. Making an eyeball - and having the servo dart it about was a no brainer.
Then, another unxpected inspiration - due to a) the "lidded box" having a roundish bottom and b) Newtons Laws of Inertia. When the servo arm swings quickly - and stops suddenly - it imparts a force on whatever it's attached to - in this case - the box it's in - and causes the box to move - jerking and rocking - just a little bit.
By turning a lead fishing weight down a bit - and connecting it to the servo's arm with shrink tubing - I could amplify THAT speed freak behavior.
By using a hyperdemic syringe and needle in place of a finial, the movement at the tip of the needle was amplified again due to its distance from the bottom of the capsule - the pivot point for the movement.
Here's a link to the quick and dirty YouTube vid I did on this accidently discovered "behavior". (hope this url is right).